[Oremem] Mount St. Helens Seismic Activity Increases Overnight

[Phillip Barker]

Hello,

I thought this would be of interest to the membership.

73,
Phil
AAR0ME

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Seismic Activity Increases Overnight

September 30, 2004
 
By KOMO Staff & News Services 

VANCOUVER, WA - Scientists say there were larger magnitude earthquakes 
late Wednesday night and early Thursday morning on Mount St. Helens.

Some of the quakes had preliminary magnitudes of 3.0. 
With the increased activity, experts are saying something may be 
imminent. It could mean an eruption -- or just some steam.

Earthquakes ranging from magnitude 2 to 2.8 were coming about four 
times a minute Wednesday, possibly weakening the lava dome in the 
crater of the 8,364-foot mountain, the U.S. Geological Survey said.

Scientists did not expect anything like the mountain's devastating 
eruption in 1980, which killed 57 people and coated towns 250 miles 
away with ash. But a small or moderate blast could coat an area three 
miles around the volcano's crater with ash and rock, scientists said.

Few people live near the mountain, which is surrounded by a national 
forest. The closest structure is the Johnston Ridge Observatory, 
about five miles from the crater.

The Geological Survey raised the mountain's eruption advisory from 
Level 1 to Level 2 out of a possible 3 on their four-leveled scale 
(from zero to 3) Wednesday, prompting officials to begin notifying 
various state and federal agencies of a possible eruption. The USGS 
also has asked the National Weather Service to be ready to track an 
ash plume with its radar system.

In addition, scientists called off a plan to have two researchers study 
water rushing from the crater's north face for signs of magma. A plane 
was still able to fly over the crater Wednesday to collect gas samples.

"An aircraft can move the hell out of the way fast," said Jeff Wynn, the 
chief scientist at the survey's Cascade Volcano Observatory. "We don't 
want anyone in there on foot."

The USGS has been monitoring St. Helens closely since last Thursday, when 
swarms of tiny earthquakes were first recorded. On Sunday, scientists 
issued a notice of volcanic unrest, closing the crater and upper flanks 
of the volcano to hikers and climbers.

Scientists said they believe the seismic activity is being caused by 
pressure from a reservoir of molten rock a little more than a mile below 
the crater. That magma apparently rose from a depth of about six miles in 
1998, but never reached the surface, Wynn said.

The mountain's eruption on May 18, 1980, blasted away its top 1,300 feet, 
spawned mudflows that choked the Columbia River shipping channel, leveled 
hundreds of square miles of forests and paralyzed towns and cities more 
than 250 miles to the east with volcanic ash.

For More Information:

St. Helens Info -- http://vulcan.wr.usgs.gov
Live Web Camera Of Mt. St. Helens -- www.fs.fed.us





Phil Barker
AAR0ME
Curry County 
Computer Services
Communication and Technical Support Manager
Gold Beach, Oregon 97444
541.247.3370 Desk